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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Biosensors".

Deadline for manuscript submissions: closed (30 June 2015) | Viewed by 88306

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Prof. Dr. Stephen Holler

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Department of Physics & Engineering Physics, Fordham University, Freeman Hall B06A, 441 E. Fordham Road, Bronx, NY 10458, USA
Interests: biological sensor development; environmental sensing; micro-optical sensors; whispering gallery mode biosensors; microcavity photonics; light scattering from bio-aerosols; fluorescence and absorption spectroscopy; cavity ringdown spectroscopy
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Special Issue Information

Dear Colleagues,

The implementation of label-free sensing of biological and chemical agents allows one to investigate the underlying physical and chemical characteristics and interactions target analytes while reducing both sample complexity and preparation time. Sensor platforms incorporating label-free detection schemes avoid the potentially confounding effects of molecular labels by monitoring the target species directly, relying solely on the intrinsic physicochemical properties of the target analyte. Because of the relatively minimal sample preparation, such approaches are well suited for field applications and remote diagnostics where either sample preparation facilities and/or trained personnel may be limited or unavailable.

Label-free detection schemes are becoming more robust and highly sensitive due to innovations in the field. These developments are opening doors to new applications and novel sensor designs. The result is a broad, interdisciplinary field that touches on many aspects of science and engineering. We seek to bring together the diversity of research and cross-pollinate ideas that would further enhance the field. To this end, we are soliciting manuscripts for a Special Issue focused on label-free detection and sensing of biological and chemical analytes, such as DNA, protein, bacteria, virus, toxic industrial materials, biological and/or chemical warfare agents, explosives, radionuclides, among others. Novel research that incorporate sensing modalities including, but not limited to, spectroscopy (absorption, fluorescence, Raman), photonics (fiber optic, interferometric, DFB, DBR), microcavities (spheres, toroids, ring resonators), plasmonic nanoparticle enhancement (spheres, shells, nanorods), micromechanical (QCM, cantilever), surface acoustic wave, surface plasmon resonance are welcome.

Dr. Stephen Holler
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

spectroscopy
photonics
microcavities
plasmonics
surface acoustic wave
mechanical oscillators
biosensors
chemical sensors

Published Papers (10 papers)

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Research

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1316 KiB

Open AccessArticle

Analysis of Surface Plasmon Resonance Curves with a Novel Sigmoid-Asymmetric Fitting Algorithm

by Daeho Jang, Geunhyoung Chae and Sehyun Shin

Sensors 2015, 15(10), 25385-25398; https://doi.org/10.3390/s151025385 - 30 Sep 2015

Cited by 12 | Viewed by 13788

Abstract

The present study introduces a novel curve-fitting algorithm for surface plasmon resonance (SPR) curves using a self-constructed, wedge-shaped beam type angular interrogation SPR spectroscopy technique. Previous fitting approaches such as asymmetric and polynomial equations are still unsatisfactory for analyzing full SPR curves and their use is limited to determining the resonance angle. In the present study, we developed a sigmoid-asymmetric equation that provides excellent curve-fitting for the whole SPR curve over a range of incident angles, including regions of the critical angle and resonance angle. Regardless of the bulk fluid type (i.e., water and air), the present sigmoid-asymmetric fitting exhibited nearly perfect matching with a full SPR curve, whereas the asymmetric and polynomial curve fitting methods did not. Because the present curve-fitting sigmoid-asymmetric equation can determine the critical angle as well as the resonance angle, the undesired effect caused by the bulk fluid refractive index was excluded by subtracting the critical angle from the resonance angle in real time. In conclusion, the proposed sigmoid-asymmetric curve-fitting algorithm for SPR curves is widely applicable to various SPR measurements, while excluding the effect of bulk fluids on the sensing layer. Full article

(This article belongs to the Special Issue Label-Free Sensing)

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2337 KiB

Open AccessArticle

An Apta-Biosensor for Colon Cancer Diagnostics

by Mojgan Ahmadzadeh Raji, Ghasem Amoabediny, Parviz Tajik, Morteza Hosseini and Ebrahim Ghafar-Zadeh

Sensors 2015, 15(9), 22291-22303; https://doi.org/10.3390/s150922291 - 03 Sep 2015

Cited by 19 | Viewed by 7602

Abstract

This paper reports the design and implementation of an aptasensor using a modified KCHA10a aptamer. This aptasensor consists of a functionalized electrodes using various materials including 11-mercaptoandecanoic acid (11-MUA) and modified KCHA10a aptamer. The HCT 116, HT 29 and HEp-2 cell lines are used in this study to demonstrate the functionality of aptasensor for colon cancer detection purposes. Flow cytometry, fluorescence microscopy and electrochemical cyclic voltammetry are used to verify the binding between the target cells and aptamer. The limit of detection (LOD) of this aptasensor is equal to seven cancer cells. Based on the experimental results, the proposed sensor can be employed for point-of-care cancer disease diagnostics. Full article

(This article belongs to the Special Issue Label-Free Sensing)

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454 KiB

Open AccessArticle

Considerations on Circuit Design and Data Acquisition of a Portable Surface Plasmon Resonance Biosensing System

by Keke Chang, Ruipeng Chen, Shun Wang, Jianwei Li, Xinran Hu, Hao Liang, Baiqiong Cao, Xiaohui Sun, Liuzheng Ma, Juanhua Zhu, Min Jiang and Jiandong Hu

Sensors 2015, 15(8), 20511-20523; https://doi.org/10.3390/s150820511 - 19 Aug 2015

Cited by 2 | Viewed by 6256

Abstract

The aim of this study was to develop a circuit for an inexpensive portable biosensing system based on surface plasmon resonance spectroscopy. This portable biosensing system designed for field use is characterized by a special structure which consists of a microfluidic cell incorporating a right angle prism functionalized with a biomolecular identification membrane, a laser line generator and a data acquisition circuit board. The data structure, data memory capacity and a line charge-coupled device (CCD) array with a driving circuit for collecting the photoelectric signals are intensively focused on and the high performance analog-to-digital (A/D) converter is comprehensively evaluated. The interface circuit and the photoelectric signal amplifier circuit are first studied to obtain the weak signals from the line CCD array in this experiment. Quantitative measurements for validating the sensitivity of the biosensing system were implemented using ethanol solutions of various concentrations indicated by volume fractions of 5%, 8%, 15%, 20%, 25%, and 30%, respectively, without a biomembrane immobilized on the surface of the SPR sensor. The experiments demonstrated that it is possible to detect a change in the refractive index of an ethanol solution with a sensitivity of 4.99838 × 10⁵ ΔRU/RI in terms of the changes in delta response unit with refractive index using this SPR biosensing system, whereby the theoretical limit of detection of 3.3537 × 10⁻⁵ refractive index unit (RIU) and a high linearity at the correlation coefficient of 0.98065. The results obtained from a series of tests confirmed the practicality of this cost-effective portable SPR biosensing system. Full article

(This article belongs to the Special Issue Label-Free Sensing)

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353 KiB

Open AccessArticle

Antigen-Antibody Affinity for Dry Eye Biomarkers by Label Free Biosensing. Comparison with the ELISA Technique

by Maríafe Laguna, Miguel Holgado, Ana L. Hernandez, Beatriz Santamaría, Alvaro Lavín, Javier Soria, Tatiana Suarez, Carlota Bardina, Mónica Jara, Francisco J. Sanza and Rafael Casquel

Sensors 2015, 15(8), 19819-19829; https://doi.org/10.3390/s150819819 - 13 Aug 2015

Cited by 11 | Viewed by 5658

Abstract

The specificity and affinity of antibody-antigen interactions is a fundamental way to achieve reliable biosensing responses. Different proteins involved with dry eye dysfunction: ANXA1, ANXA11, CST4, PRDX5, PLAA and S100A6; were validated as biomarkers. In this work several antibodies were tested for ANXA1, ANXA11 and PRDX5 to select the best candidates for each biomarker. The results were obtained by using Biophotonic Sensing Cells (BICELLs) as an efficient methodology for label-free biosensing and compared with the Enzyme-Linked Immuno Sorbent Assay (ELISA) technique. Full article

(This article belongs to the Special Issue Label-Free Sensing)

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1008 KiB

Open AccessArticle

PEG Functionalization of Whispering Gallery Mode Optical Microresonator Biosensors to Minimize Non-Specific Adsorption during Targeted, Label-Free Sensing

by Fanyongjing Wang, Mark Anderson, Matthew T. Bernards and Heather K. Hunt

Sensors 2015, 15(8), 18040-18060; https://doi.org/10.3390/s150818040 - 24 Jul 2015

Cited by 32 | Viewed by 8361

Abstract

Whispering Gallery Mode (WGM) optical microresonator biosensors are a powerful tool for targeted detection of analytes at extremely low concentrations. However, in complex environments, non-specific adsorption can significantly reduce their signal to noise ratio, limiting their accuracy. To overcome this, poly(ethylene glycol) (PEG) can be employed in conjunction with appropriate recognition elements to create a nonfouling surface capable of detecting targeted analytes. This paper investigates a general route for the addition of nonfouling elements to WGM optical biosensors to reduce non-specific adsorption, while also retaining high sensitivity. We use the avidin-biotin analyte-recognition element system, in conjunction with PEG nonfouling elements, as a proof-of-concept, and explore the extent of non-specific adsorption of lysozyme and fibrinogen at multiple concentrations, as well as the ability to detect avidin in a concentration-dependent fashion. Ellipsometry, contact angle measurement, fluorescence microscopy, and optical resonator characterization methods were used to study non-specific adsorption, the quality of the functionalized surface, and the biosensor’s performance. Using a recognition element ratio to nonfouling element ratio of 1:1, we showed that non-specific adsorption could be significantly reduced over the controls, and that high sensitivity could be maintained. Due to the frequent use of biotin-avidin-biotin sandwich complexes in functionalizing sensor surfaces with biotin-labeled recognition elements, this chemistry could provide a common basis for creating a non-fouling surface capable of targeted detection. This should improve the ability of WGM optical biosensors to operate in complex environments, extending their application towards real-world detection. Full article

(This article belongs to the Special Issue Label-Free Sensing)

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1194 KiB

Open AccessArticle

A Sensitive and Selective Label-Free Electrochemical DNA Biosensor for the Detection of Specific Dengue Virus Serotype 3 Sequences

by Natália Oliveira, Elaine Souza, Danielly Ferreira, Deborah Zanforlin, Wessulla Bezerra, Maria Amélia Borba, Mariana Arruda, Kennya Lopes, Gustavo Nascimento, Danyelly Martins, Marli Cordeiro and José Lima-Filho

Sensors 2015, 15(7), 15562-15577; https://doi.org/10.3390/s150715562 - 01 Jul 2015

Cited by 65 | Viewed by 12505

Abstract

Dengue fever is the most prevalent vector-borne disease in the world, with nearly 100 million people infected every year. Early diagnosis and identification of the pathogen are crucial steps for the treatment and for prevention of the disease, mainly in areas where the co-circulation of different serotypes is common, increasing the outcome of dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Due to the lack of fast and inexpensive methods available for the identification of dengue serotypes, herein we report the development of an electrochemical DNA biosensor for the detection of sequences of dengue virus serotype 3 (DENV-3). DENV-3 probe was designed using bioinformatics software and differential pulse voltammetry (DPV) was used for electrochemical analysis. The results showed that a 22-m sequence was the best DNA probe for the identification of DENV-3. The optimum concentration of the DNA probe immobilized onto the electrode surface is 500 nM and a low detection limit of the system (3.09 nM). Moreover, this system allows selective detection of DENV-3 sequences in buffer and human serum solutions. Therefore, the application of DNA biosensors for diagnostics at the molecular level may contribute to future advances in the implementation of specific, effective and rapid detection methods for the diagnosis dengue viruses. Full article

(This article belongs to the Special Issue Label-Free Sensing)

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460 KiB

Open AccessArticle

A Label-Free Impedimetric DNA Sensor Based on a Nanoporous SnO₂ Film: Fabrication and Detection Performance

by Minh Hai Le, Carmen Jimenez, Eric Chainet and Valerie Stambouli

Sensors 2015, 15(5), 10686-10704; https://doi.org/10.3390/s150510686 - 06 May 2015

Cited by 24 | Viewed by 6768

Abstract

Nanoporous SnO₂ thin films were elaborated to serve as sensing electrodes for label-free DNA detection using electrochemical impedance spectroscopy (EIS). Films were deposited by an electrodeposition process (EDP). Then the non-Faradic EIS behaviour was thoroughly investigated during some different steps of functionalization up to DNA hybridization. The results have shown a systematic decrease of the impedance upon DNA hybridization. The impedance decrease is attributed to an enhanced penetration of ionic species within the film volume. Besides, the comparison of impedance variations upon DNA hybridization between the liquid and vapour phase processes for organosilane (APTES) grafting on the nanoporous SnO₂ films showed that vapour-phase method is more efficient. This is due to the fact that the vapour is more effective than the solution in penetrating the nanopores of the films. As a result, the DNA sensors built from vapour-treated silane layer exhibit a higher sensitivity than those produced from liquid-treated silane, in the range of tested target DNA concentration going to 10 nM. Finally, the impedance and fluorescence response signals strongly depend on the types of target DNA molecules, demonstrating a high selectivity of the process on nanoporous SnO₂ films. Full article

(This article belongs to the Special Issue Label-Free Sensing)

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Review

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4856 KiB

Open AccessReview

Label-Free Biosensor Imaging on Photonic Crystal Surfaces

by Yue Zhuo and Brian T. Cunningham

Sensors 2015, 15(9), 21613-21635; https://doi.org/10.3390/s150921613 - 28 Aug 2015

Cited by 57 | Viewed by 9090

Abstract

We review the development and application of nanostructured photonic crystal surfaces and a hyperspectral reflectance imaging detection instrument which, when used together, represent a new form of optical microscopy that enables label-free, quantitative, and kinetic monitoring of biomaterial interaction with substrate surfaces. Photonic Crystal Enhanced Microscopy (PCEM) has been used to detect broad classes of materials which include dielectric nanoparticles, metal plasmonic nanoparticles, biomolecular layers, and live cells. Because PCEM does not require cytotoxic stains or photobleachable fluorescent dyes, it is especially useful for monitoring the long-term interactions of cells with extracellular matrix surfaces. PCEM is only sensitive to the attachment of cell components within ~200 nm of the photonic crystal surface, which may correspond to the region of most interest for adhesion processes that involve stem cell differentiation, chemotaxis, and metastasis. PCEM has also demonstrated sufficient sensitivity for sensing nanoparticle contrast agents that are roughly the same size as protein molecules, which may enable applications in “digital” diagnostics with single molecule sensing resolution. We will review PCEM’s development history, operating principles, nanostructure design, and imaging modalities that enable tracking of optical scatterers, emitters, absorbers, and centers of dielectric permittivity. Full article

(This article belongs to the Special Issue Label-Free Sensing)

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3367 KiB

Open AccessReview

Raman Spectroscopy of Optically Trapped Single Biological Micro-Particles

by Brandon Redding, Mark J. Schwab and Yong-le Pan

Sensors 2015, 15(8), 19021-19046; https://doi.org/10.3390/s150819021 - 04 Aug 2015

Cited by 54 | Viewed by 8484

Abstract

The combination of optical trapping with Raman spectroscopy provides a powerful method for the study, characterization, and identification of biological micro-particles. In essence, optical trapping helps to overcome the limitation imposed by the relative inefficiency of the Raman scattering process. This allows Raman spectroscopy to be applied to individual biological particles in air and in liquid, providing the potential for particle identification with high specificity, longitudinal studies of changes in particle composition, and characterization of the heterogeneity of individual particles in a population. In this review, we introduce the techniques used to integrate Raman spectroscopy with optical trapping in order to study individual biological particles in liquid and air. We then provide an overview of some of the most promising applications of this technique, highlighting the unique types of measurements enabled by the combination of Raman spectroscopy with optical trapping. Finally, we present a brief discussion of future research directions in the field. Full article

(This article belongs to the Special Issue Label-Free Sensing)

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2136 KiB

Open AccessReview

Diamond Nanowires: A Novel Platform for Electrochemistry and Matrix-Free Mass Spectrometry

by Sabine Szunerits, Yannick Coffinier and Rabah Boukherroub

Sensors 2015, 15(6), 12573-12593; https://doi.org/10.3390/s150612573 - 27 May 2015

Cited by 39 | Viewed by 8245

Abstract

Over the last decades, carbon-based nanostructures have generated a huge interest from both fundamental and technological viewpoints owing to their physicochemical characteristics, markedly different from their corresponding bulk states. Among these nanostructured materials, carbon nanotubes (CNTs), and more recently graphene and its derivatives, hold a central position. The large amount of work devoted to these materials is driven not only by their unique mechanical and electrical properties, but also by the advances made in synthetic methods to produce these materials in large quantities with reasonably controllable morphologies. While much less studied than CNTs and graphene, diamond nanowires, the diamond analogue of CNTs, hold promise for several important applications. Diamond nanowires display several advantages such as chemical inertness, high mechanical strength, high thermal and electrical conductivity, together with proven biocompatibility and existence of various strategies to functionalize their surface. The unique physicochemical properties of diamond nanowires have generated wide interest for their use as fillers in nanocomposites, as light detectors and emitters, as substrates for nanoelectronic devices, as tips for scanning probe microscopy as well as for sensing applications. In the past few years, studies on boron-doped diamond nanowires (BDD NWs) focused on increasing their electrochemical active surface area to achieve higher sensitivity and selectivity compared to planar diamond interfaces. The first part of the present review article will cover the promising applications of BDD NWS for label-free sensing. Then, the potential use of diamond nanowires as inorganic substrates for matrix-free laser desorption/ionization mass spectrometry, a powerful label-free approach for quantification and identification of small compounds, will be discussed. Full article

(This article belongs to the Special Issue Label-Free Sensing)

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